Variable speed drive control

ABSTRACT

A variable speed drive control system for textile twisting apparatus is disclosed. The system includes two variable sheave pulleys, one of which is caused to vary by a lever driven by an air cylinder. Movement of the air cylinder is controlled by a closed-loop hydraulic system controlled by an electrical timer.

States atent 1 Hooper 11] 3,867,248 [4 1 Apr. 30, 1974 VARIABLE SPEED DRIVE CONTROL [76] Inventor: Robert P. Hooper, 111 Steeplechase Rd., Devon, Pa. 19333 [22] Filed: May 22, 1972 [21] Appl. No.: 255,330

[52] US. Cl 747230.17 F, 74/230.l7 A [51] Int. Cl F165 5/52 [58] Field of Search 74/230. 17 A, 230.17 F;

[56] References Cited UNITED STATES PATENTS 1,545,638 7/1925 Clay 74/230.l7 F

3,731,549 5/1973 Kaiser 74/230.17 F 2,731,849 1/1956 ROCkWOOd 74/230.l7 F

3,332,224 7/1967 Joy t 1 57/95 3,138,033 6/1964 Glasson... 74/230.17 A 2,660,069 11/1953 Home i. 74/230.17 F

1,851,484 Bausman 188/313 3,043,152 7/l962 Karig 74/230.17 F

2,306,541 12/1942 Clay 74/230.17 F 2,803,143 8/1957 Michie 74/230.l7 A

FOREIGN PATENTS OR APPLICATIONS 570,030 I 6/1945 Great Britain 188/313 631,375 12/1961 Italy 74/230.l7 F

Primary ExaminerCharles J. Myhre Assistant ExaminerR. 1-1. Lazarus Attorney, Agent, or FirmSynnestredt & Lechner 5 7] ABSTRACT A variable speed drive control system for textile twisting apparatus is disclosed. The system includes two variable sheave pulleys, one of which is caused to vary by a lever driven by an air cylinder. Movement of the air cylinder is controlled by a closed-loop hydraulic system controlled by an electrical timer.

4 Claims, 5 Drawing Figures VARIABLE SPEED DRIVE CONTROL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to variable speed drive arrangements and control systems and particularly a drive arrangement for twisters used to wind yarn onto bobbins or tubes. v

Twisters are well known and usually comprise a plurality of spindles driven by a common drive belt. En-

gagement of the spindle mechanism by the drive belt effects rotation of the spindle and of removable bobbins which are placed on the spindles. A twist is applied to yarn being wound on a bobbin by the use of a traveler that engages the yarn and travels about the bobbin. The travelers are relatively light weight and revolve about the bobbin on a traveler ring. The traveler ring is caused to traverse the bobbin axially so that the yarn is wound substantially on the entire length of the bobbin. t

It has been common to drive the spindles at a constant speed throughout the wind up period or doff of the bobbin. However, constant speed winding produces a bobbin package wherein the tension of the yarn wound on the bobbin is not uniform; the tension of the yarn decreases as the diameter of the yarn package increases. Thus, the layers of yarn wound close to the bobbin core are more tightly wound and form a dense core, whilethe layers of yarn adjacent the exterior of the package are wound with lesser tension, and form a soft, less dense package segment.

The reason for this phenomenon appears to be that as the package size increases, the angular velocity of the traveler decreases, and the angle formed between the incoming yarn andthe package decreases. As this occurs, the traveler exerts less and less force on the incoming yarn thereby decreasing the tension with which the yarn is wound on the package.

The non-uniformity in tension of the yarn package is undesirable from several standpoints. A lesser amount of yarn is wound into the package. Textile goods knitted from such packages show undesirable density variations and dyeing variations. To overcome the nonuniformity of tension, additional constant-tensioning devices must be used either when back winding the yarn from the bobbin to a shipping-package or on the knitting machines utilizing the yarn packages as the yarn is supplied from the supply package.

2. Description of the Prior Art One manner of maintaining the tension of the yarn on the package uniform has been to control the speed of the spindle during the doff of the bobbin so that, as the size of the package increases, .the speed of the spindle is increased, thereby maintaining the yarn tension uniform. A drive system and control for gradually increasing the spindle speed is known in which thereis used a drive arrangement utilizing variable sheave pulleys for maintaining different driving speeds. Speed changes are accomplished under the control of an electromechanical systernemploying a constant speed motor and a gear train to effectuate movement of the movable sheave. i

SUMMARY OF THE INVENTION The present invention comprises a variable speed drive system particularly adapted for use with yarn twisting apparatus. The system includes variable sheave pulleys interposed between a drive motor and a power output shaft. Control of the position of the variable sheave is achieved by an air cylinder, the stroke of BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall schematic view of the variable speed drive system of the present invention.

FIG. 2 is a top view of the drive system schematically illustrated in FIG. 1. a

FIG. 3 is a schematic illustration of the drive control 1 circuit for the present invention.

FIG. 4 is a schematic illustration of a motor control circuit for the present invention.

FIG. 5 is a graph showing the variation in spindle speeds with respect to time for a typical program.

Turning now to .the preferred embodiment of the invention,.there is shown in FIG, 1 a main frame 10 on which is mounted motor M. The output shaft 12 of motor M has mounted thereon a variable sheave drive pulley l5 comprised of fixed sheave 14 and movable sheave 16. The sheaves 14 and 16 form between them a generally V-type drive pulley.

Also on the main frame 10 is support 22 in which is rotatably received jack-shaft 24. Meansare provided for. preventing axial movement of jack shaft 24 relative to support 22. Jack shaft 24 has mounted thereon a variable pulley comprises of movable sheave 26 and fixed sheave 28. Drive belt 20 is entrained over pulleys l5 and 25 to transmit power from motor M to jack shaft 24. A pulley or similar drive member 32 is affixed to the other end of shaft 24 to receive a drive member such as belt 34 for driving the spindles of a textile twisting machine, for example a downtwister. As is conventiona'l, a resilient biasing member 18, for instance, a compression spring, yieldably biases movable sheave 26 toward fixed sheave 28. The yieldable biasing means 18 allows the sheave 26 to move axially along shaft 24.

The movable sheave 16 of variable pulley 15 is caused to move axially along shaft 12 by a drive system which includes lever 36. Lever 36 is pivotally attached at one end to fixed pivot 40 and is also pivotally attached as at 42, for instance, by a clevis-type arrangement, to drive rod 44 of air cylinder 52. A flanged collar 30, affixed to sheave 16, is received in a yoke or similar element carried by lever 36.

Arcuate movement of lever 36 about pivot 40 causes collar 30 to be moved axially along shaft 12. Movement of collar 30 in turn causes axial movement of sheave 16 thereby causing a change in the effective diameter of pulley 15. As the centerline distance between shafts 12 and 24 'is fixed, changes in the diameter of pulley 15 must be compensated by a corresponding change in diameter of pulley 25. This is accomplished by the resilient mounting of sheave 26, as heretofore described, which allows the effective diameter of pulley 25 to vary inversely as the effective diameter of drive pulley 15 is varied.

Lever 36 is moved by air cylinder 52 acting through drive rod 44. A two-way valve 56 controls the supply of air from compressed air source 58 to air Cylinder 52.

Movement of collar 30 and movable sheave 16 toward the fixed sheave 14 causes an increase in the effective diameter of pulley 15. Assuming the motor M drives pulley 15 at a constant speed, the increase in diameter of pulley 15 will cause jack shaft 24 to rotate at a faster speed. Conversely, movement of sheave 16 away from fixed sheave 14 will decrease the effective diameter of pulley 25 and cause a decrease in the speed of rotation of jack shaft 24.

A control means imposedon drive rod 44 comprises a hydraulic cylinder 60. The hydraulic cylinder 60 includes a movable piston P which is mounted to a piston rod 68. Fluid tight chambers A and B are formed on either side of piston P in hydraulic cylinder 60. The volumes of chambers A and B vary with respect to each,

other in accordance with the movement of piston P in cylinder 60. Chambers A and B are interconnected to each other by a fluid tight conduit 62. Included in the conduit 62 is an electrically controlled valve 64 and an .justably positionable along piston rod 68. To this end,

a portion of piston rod 78 can be threaded and stop members 70 and 72 received on this threaded portion.

Link 50 interconnects piston rod 68 with drive rod 44 of air cylinder 52. Link 50 is fixed to drive rod 44, as by threaded fasteners 46. The link 50 is positioned to engage stop members 70 and 72 on piston rod 68.

At the start of the operating cycle, the drive rod 44 of air cylinder 52 is in an extended position, with link 50 disposed against low speed stop member 72 of piston rod 68, asshown in FIG. 1. The operating sequence is begun by a manually actuated program start switch PSS (FIG. 3). When actuated, switch PSS actuates valve 56 to supply air under pressure to air cylinder 52 so that drive rod 44 is caused to retract into cylinder 52. As the drive rod 44 is retracted into the air cylinder 52, drive rod 44 rotates lever 36 to causes about fixed pivot 40. The yoke of lever 36 causes collar 30, and thus sheave 16 to be pulled toward fixed sheave 14. As this occurs, the effective diameter of pulley 15 becomes larger and the effective diameter of pulley 25 becomes smaller thereby increasing the speed of rotation of jack shaft 24. As the rotational speed of jack shaft 24 increases, the belt 34 will be driven faster and the speed of the spindles driven by the belt will inlink 50 abuts stop member 70, further inward movement of drive rod 44 is precluded, as will hereinafter.

' The hydraulic cylinder 60'and conduit 62 constitute be explained a closed loop system containing an incompressible fluid. When link bears against stop member 70, an

axially directed force is placed on piston rod 68. If

valve 64 is closed, movement of fluid from chamber A through conduit 62 is prevented, thereby preventing movement of piston? and piston rod 68. Stop 70, engaged by link 50, holds drive rod 44 against further movement. Momentarily opening valve 64, control of which is described below, allows a small amount of fluid to flow through conduit 62 thereby allowing the piston in hydraulic cylinder to move in a direction to decrease the size of chamber A. Once the piston P of hydraulic cylinder 60 is free to move, piston rod 68 is also free to move, thereby allowing further inward movement of drive rod 44. This in turn allows a further movement of lever 36 and a corresponding increase in the effective diameter of pulley 25. This allows a corresponding increment in speed of the spindles as depicted at point III in the graph of FIG. 5. a

In FIG. 3 is shown a control circuit for air cylinder 52 and hydraulic cylinder 60. At the start of operation, manual start switch PS is actuated, thereby energizing control relay CR1. Once control relay CR1 is actuated, a holding circuit for relay CR1 is established through normally closed contacts CR2, of relay CR2 and the contacts of CR1, of relay CR The actuation of control relay CR1 in turn causes the energization of solenoid 'R of valve 56 through the normally closed contacts in ME and through the: closed contacts CRl of control relay CR1. Energization of solenoid R causes valve 56 to be placed in a position to causeair cylinder 52 to retract drive rod 44.

Actuation of starter switch PSS also causes the start up of timer T which begins to run continuously because of the holding circuit established through contacts CR2, and CR1,. Timer T emits pulses of predetermined duration at a predetermined frequency. The pulse frequency and pulse duration of timer T are readily adjustable so as to be adaptable to a wide range of programs. Timer T is a commercially available unit of conventional design and no further detailed disclosure of this element is necessary.

The output of timer Tcontrols the opening of valve 64 through timer contacts TC, valve 64 remaining open for the duration of the output pulse of timer T. The

drive speed of shaft 24 is controlled by timer T throughout the program as shown in the segment ll to IV of the program chart shown of FIG. 5. Incremental increases in speed continue during the doff, which may be over many hours in duration.

The doff is terminated by a signal produced by a yarn yardage counter (not shown) or doff timer (not shown) in the following manner. When contacts CS of the yardage counter or doff timer are closed, relays CR2 and CR3 are energized. This causes normally closed contacts CR1 to open thereby causing relay CR1 and timer T to be de-energized. De-energization of relay CR1 opens contacts CR1 thereby dropping out solenoid R of air valve 56. Also, when relay CR2 isenergized, contacts CR2 are closed thereby holding open valve 64 and contacts CR2 are closed thereby causing solenoid E to be energized to supply air to air cylinder 52 n a mannerto extend drive rod 44. Asvalve 64 is held open, the piston P of hydraulic cylinder 60 is free to move fluid from chamber B through the conduit 62 to chamber A. The only control exerted on drive rod 44 by hydraulic cylinder 60 is the rate of extension of drive rod 44 by reason of the existance of bleed orifice 66. Thus, when the speed program has ended, the drive system is caused to resume its initial starting position, the drive rod 44 is extended and the spindle speeds drop to the base speed established by low speed stop 72. Tl-Iis is represented by the segment IV-V in the graph of FIG. 5. Resetting the yarn yardage counter, thereby opening contacts CS, causes relay CR2 to be de-energized and the program is thereby returned to its initial starting conditions. The bleed orifice 66 in conduit 62 controls the maximum velocity of the fluid flowing through conduit 62, and in conjunction with the pulse frequency and pulse duration settings of timer T, establishes the parameters controlling the incremental movement of piston rod 68. This in turn determines the amount of step up in speed occurring at each timer pulse. As these parameters are not varied during program operation, the incremental increases in speed brought about by opening valve 64 will be substantially constant.

Control of the motor M is accomplished by the circuit illustrated in FIG. 4. At the start of operations, a manually actuable motor start switch M88 is actuated,

thereby energizing motor start relay MS. The motorstart relay MS includes contacts MS which are closed to form a holding circuit comprised of normally closed contact CR3: and contact M5 In parallel circuit relationship with the contact CR3 is the limit switch LS, which is engagable by the link 50, as shown in FIG. 1 and the traveler ring limit switch RS which is positioned to be engaged by the traveler ring (not shown) just after it begins its upward travel from its bottommost position. The effect of this parallel network is to establish three conditions which must be satisfied before the supply of power to the motor M has terminated. First, it will be recalled that the yardage counter closes the contacts CS thereby causing energization of relay CR3 thereby opening normally closed contacts CR3 Also,

the limit switch LS is positioned adjacent the low speed stop 72 to be engaged to the link 50 when the drive rod 44 has positioned pulley in its base speed position. Thus, limit switch LS will remain closed until opened by the return positioning of link 50. Thering traveler switch RS will remain closed until the ring traveler reaches a desired stopping position. Only when all the 1 switches CR3 LS, and RS are opened will the holding circuit to motor start relay MS be broken, thereby terminating the supply of power to motor M.

The automatic functioning of the disclosed 'drive system can be explained with reference to the graph of FIG. 5. At time T equal to 0, the motorswitch M85 is actuated and spindle speed rises to an initial start up at speed I, for example 4,000 rpm, in a time period of 5 to 10 seconds. At this point, the program start switch PS5 is energized and the drive rod 44 begins to retract into air cylinder 52. The progress of link 50 along piston rod 68 will be unimpeded between the stops 72 and 70, thereby allowing an increase in speed as shown in segment 1-11 of the graph. This period is normally about seconds in duration. At the point II, link 50 will abut high speed stop 70 and further movement of drive rod 44 will be prevented until valve 64 is opened by the timer T. The speed of the spindles at point II corresponds to a base program speed. As the timer T pulses,

the speed increases in very gradual steps as at II to III, and in a typical instance, a step may represent an increase in spindle speed of 10 to 12 rpm. At the point IV, the yardage counter reaches its predetermined setting and the contacts CS are closed thereby causing the drive rod 44 to be extended from the air cylinder 52 thereby causing a rapid decrease in drive speed represented by the graph segment lV-V. This reduction of speed may have a duration of about 20 seconds. The spindle speed at point V is the initial start up speed as established by the low speed stop 72 on piston rod 68. At the point V, the supply of power to motor M is interrupted by the occurrence of the last condition established by the parallel circuit discussed in connection with FIG. 4 above and the drive speed falls off rapidly to zero.

Thus, it can be seen that the system hereinabove disclosed provides an effective and low cost variable drive system of high reliability. Simple adjustment procedures of such elements as the timer, the bleed orifice, and the high and low speed stops and 72 respectively can accommodate the system to an extremely wide range of speed programs. Moreover, as the great majority of industrial plants have inplant sources of compressed air, there is no need for an expenditure for an additional source of motive force. to move the variable sheave pulleys. Further, use of a closed loop hydraulic cylinder in conjunction with the air cylinder eliminates the need for costly hydraulic pumps and the like.- Further, there is no need for additional programming elements such as changeable gear trains, program cards, and similar elements. Further, the use of a fluid control element yields smoother, less abrupt speed changes throughout the program cycle, thereby enhancing equipment life.

' I claim:

1. In a variable speed drive system for yarn twisting apparatus having a pair of variable sheave pulleys, a drive belt interconnecting the pulleys, a drive member driven by one of the pulley, a movable member, means coactive between the movable member and one of said pulley for varying the effective diameter of said pulley in response to movement of the movable member, and a fluid motor for moving the movable member, control means for controlling the movement of the movable means comprising, an hydraulic cylinder, a piston movable in the cylinder and forming a chamber of variable volume on each side of the piston, a quantity of a substantially incompressible fluid contained in the chambers, conduit means for providing fluid communication between the chambers, valve means for controlling the flow of said fluid through the conduit whereby movement of the piston in the cylinder is allowed or prevented, timing means for controlling the valve means whereby the valve means is opened at timed intervals to allow the flow of fluid through the conduit, and means interconnecting the piston and the movable member for allowing movement of the movable member responsive to the flow of fluid in the conduit.

' 2. Apparatus according to claim 1 wherein the movable member is a pivotted lever.

3. Apparatus according to claim 1 wherein the fluid motor is an air cylinder having a movable piston, a drive rod driven by the piston, and wherein the interconnecting means includes a link mounted on the drive rod, a piston rod fixed to the piston in the hydraulic cylinder, at least one stop element on the piston rod and means carried by the link for engaging the stop element.

4. Apparatus according to claim 1 and further including motor means for driving one of said pulleys. 

1. In a variable speed drive system for yarn twisting apparatus having a pair of variable sheave pulleys, a drive belt interconnecting the pulleys, a drive member driven by one of the pulley, a movable member, means coactive between the movable member and one of said pulley for varying the effective diameter of said pulley in response to movement of the movable member, and a fluid motor for moving the movable member, control means for controlling the movement of the movable means comprising, an hydraulic cylinder, a piston movable in the cylinder and forming a chamber of variable volume on each side of the piston, a quantity of a substantially incompressible fluid contained in the chambers, conduit means for providing fluid communication between the chambers, valve means for controlling the flow of said fluid through the conduit whereby movement of the piston in the cylinder is allowed or prevented, timing means for controlling the valve means whereby the valve means is opened at timed intervals to allow the flow of fluid through the conduit, and means interconnecting the piston and the movable member for allowing movement of the movable member responsive to the flow of fluid in the conduit.
 2. Apparatus according to claim 1 wherein the movable member is a pivotted lever.
 3. Apparatus according to claim 1 wherein the fluid motor is an air cylinder having a movable piston, a drive rod driven by the piston, and wherein the interconnecting means includes a link mounted on the drive rod, a piston rod fixed to the piston in the hydraulic cylinder, at least one stop element on the piston rod and means carried by the link for engaging the stop element.
 4. Apparatus according to claim 1 and further including motor means for driving one of said pulleys. 